Donnelly, a gun-rights advocate, outspoken critic of illegal immigration and social conservative, said he is unfazed by a state electorate that leans far to his political left. He says his ``guerrilla grass-roots'' campaign will offer voters an alternative to the high taxes and what he calls government interference offered by Brown and his fellow Democrats.

``I can unite the divided majority that makes up California: people who work hard, who play by the rules and just want to be left alone by their government,'' Donnelly, 47, said in a telephone interview with The Associated Press.

Yet his candidacy, along with that of former lawmaker and Lt. Gov. Abel Maldonado, a moderate Republican, is unlikely to receive a warm welcome from the GOP establishment. After decades of sinking registration numbers, the party has sought to rebrand itself so it can appeal to a wider variety of voters, including Latinos.

Many party delegates had hoped to shift the party to the political center and keep the focus off the divisive issues that have been central to Donnelly's previous campaigns, including his history as a former Minuteman border enforcer.

Mindful of the need to connect with a broader base of voters, Donnelly on Tuesday was flanked by a diverse group of supporters at the furniture factory in the Los AngelesCounty city of Baldwin Park where he announced his candidacy.

The official filing period to run for governor does not begin until Feb. 10.

Next year is the first in which the primary for governor will be a top-two, in which both leading candidates will move on to the general election regardless of party affiliation.

Whoever emerges will face a daunting challenge in Brown, the 75-year-old governor who returned to office in 2011 after first serving from 1975 to 1983. Brown has yet to announce a bid for re-election, but there is little doubt that he will run.

After becoming the longest-serving governor earlier this month, Brown quipped last week that: ``I'm only in the third year of my first of my second terms.''

Brown has a 49 percent approval rating among likely voters, according to a September Public Policy Institute of California poll and has nearly $16 million in his two campaign committees. He also successfully shepherded a budget through the state Legislature this year with little drama after voters approved billions of dollars in temporary sales and income taxes last year.